In an airbag device for a front passenger seat, an airbag in a folded state is accommodated within a container, on the top of which a cover is attached in a way that the airbag is covered. Upon vehicle collision, an inflator is activated so that the airbag is deployed toward the inside of a vehicle to protect a passenger.
It is regulated by law that an instrument panel shall have a characteristic of being concavely deformed so as to absorb a relatively small impact force (the instrument panel impact regulation). The relatively small impact force is such impact force that is not large enough to develop the airbag and occurs when a passenger hits the instrument panel due to a collision while the vehicle travels at low speed.
The container of the airbag device for a front passenger seat is required to have a deformable property so as to satisfy the instrument panel impact regulation, while the container is required to have strength that it is not significantly deformed even if pressed from the inside by the developing airbag. Thus, the airbag device, in which the entire container is made fragile in order to clear the instrument panel impact regulation, is insufficient.
In Japanese Patent Publication No. H08-225049A, there is disclosed an airbag device includes a container having an opened front surface of a box shape, which is composed of a rear half section to which an inflator is attached and of a front half section which is attached in a way that when impact force is applied from an instrument panel it can move backward in relation to the rear half section. When the impact force to the instrument panel presses the instrument panel and a lid (cover), the front half section of the container moves backward, so that deformation of the instrument panel is not affected by the container. It is also explained that the container has sufficient strength capable of withstanding the impact due to airbag deployment and is rapidly deformable when large impact force is applied from the instrument panel.
[Patent Document 1]
Japanese Patent Publication No. H08-225049A